Device and method for sensing electrical activity in tissue

ABSTRACT

An exemplary embodiment providing one or more improvements includes apparatus and methods for sensing electrical activity in tissue of a person in a manner which is substantially limits or eliminates interference from noise in a surrounding environment.

RELATED APPLICATIONS

This patent arises from a continuation of U.S. application Ser. No.15/156,866 (now U.S. Pat. No. 10,506,941), titled “Device and Method forSensing Electrical Activity in Tissue,” filed May 17, 2016, which is acontinuation of U.S. patent application Ser. No. 11/500,678 (now U.S.Pat. No. 9,351,658), titled “Device and Method for Sensing ElectricalActivity in Tissue,” filed Aug. 8, 2006, which claims the benefit ofU.S. Provisional Application No. 60/713,899, filed on Sep. 2, 2005. Inaddition, U.S. patent application Ser. No. 11/500,678 arises from acontinuation of U.S. patent application Ser. No. 11/500,679, titled “ADevice and Method for Determining and Improving Present Time EmotionalState of a Person,” filed Aug. 8, 2006, which claims the benefit of U.S.Provisional Application No. 60/706,580, filed Aug. 9, 2005. U.S. patentapplication Ser. Nos. 15/156,866; 11/500,678; and 11/500,679 and U.S.Provisional Application Nos. 60/713,899 and 60/706,580 are herebyincorporated by reference in their entireties.

BACKGROUND

Devices used for sensing electrical activity in tissue have many uses inmodern society. In particular modern electroencephalograms (EEGs) areused for measuring electrical activity in the brains of people foranesthesia monitoring, attention deficit disorder treatment, epilepsyprediction, and sleep monitoring, among other uses. Unfortunately, thecomplexity and cost of prior modern EEGs typically limits their use toclinics or other facilities where the device can be used on numerouspeople under the expert attention of a trained medical professional.Using the EEG on numerous people in a clinical setting helps todistribute the cost of the machine to the people which use it. EEGs cancost several thousand dollars.

Trained personnel are used for setting up and operating EEGs because ofthe complexities involved. Setting up prior EEGs involves preparing theskin of the person for connection of electrodes. The skin is typicallyprepared by shaving the hair from the area, sanding the skin to removethe outer surface and applying a conductive gel or liquid to the skinbefore attaching the electrode to the skin. Such extensive skinpreparation is needed because contact resistance between the electrodeand the skin must be reduced in order for prior EEGs to work properly.Contact resistance in these prior EEGs typically needs to be 20 k ohmsor less.

Typical prior EEGs are subject to errors caused by electrical andmagnetic noise from the environment surrounding the person. Errors arealso caused by slight variations in internal components of the EEG andother sources, such as movement of the person during the operation ofthe EEG. Environmental noise can be caused by 60 Hz power in electricalwiring and lights in the area where the EEG is used, and other sources.Even the friction of any object moving through the air can cause noisefrom static electricity. Most or all prior EEGs have two electrodes areconnected to the person's head and wires which are run from each of theelectrodes to the EEG machine. The routing of the wires and thepositions of the noise causing elements in the environment can causesignificant errors in the measurements done by the EEG.

Measuring the electrical activity in the brain is difficult because theelectrical signal being measured is many times smaller than the noise inthe system. In many instances, the noise is on the order of a few voltsor a few tens of volts while the electrical signal being measured isonly in the microvolt range. This gives a signal-to-noise ratio of 10 6.

Prior EEGs have used very precise differential amplifiers, such asinstrumentation amplifiers, to measure the electrical signal. Theamplifier is referenced to a common reference such as the leg of theuser. Each of the two wires from the two electrodes on the person's headare connected to the inputs of the differential amplifier. The output ofthe differential amplifier is a voltage relative to the reference whichis proportional to the difference in voltage between the two electrodestimes a constant. The measurement in this case is very sensitive becausethe differential amplifier is finding a small difference, the brainsignal, between two signals which are 10{circumflex over ( )}6 times aslarge. These are reasons why small variations in components, the routingof the wires and other factors cause significant errors in themeasurement and why prior EEGs are expensive and hard to use.

Another problem with the prior EEGs is that the 60 Hz noise is amplifiedat the first stage which saturates the signals before they aresubtracted. In prior EEGs, designers go to great lengths to designsystems that balance or shield the noise to avoid saturation. Systemswhich use the principle of subtracting two large numbers in measuring asmall number are prone to these kinds of problems.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon reading of the specification and a study of the drawings.

SUMMARY

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tools and methods which aremeant to be exemplary and illustrative, not limiting in scope. Invarious embodiments, one or more of the above-described problems havebeen reduced or eliminated, while other embodiments are directed toother improvements.

A method is described for sensing electrical activity in tissue of auser. Electrical activity is detected from the tissue between a firstpoint and a second point on skin of the user and a voltage signal isgenerated in response thereto which contains a signal of interest andundesired signals. The voltage signal is amplified to amplify the signalof interest and undesired signals without substantially amplifying thenoise. The amplification results in an output signal.

Another method is disclosed for sensing electrical activity in tissue ofa user in a noise environment that is subjected to electrical noise. Asensor electrode is connected to skin of the user at a first point. Areference electrode is connected to skin of the user at a second pointwhich is in a spaced apart relationship to the first point to allow thesensor electrode to sense the electrical activity in the tissue at thefirst point relative to the second point. An amplifier is provided whichis configured to amplify the electrical activity while substantiallyreducing the influence from the noise environment.

A sensor circuit is described for sensing electrical activity in tissueof a user and isolating and amplifying a signal of interest from thesensed electrical activity. The sensor circuit includes a sensorelectrode for placing on skin of the user at a first point. A referenceelectrode for placing at a second point which is a distance away fromthe first point to allow the sensor electrode to sense the electricalactivity and to produce a voltage signal relative to the second pointwhich includes the signal of interest in response. An electronic moduleof the sensor circuit includes a power source with positive and negativesource voltages and a source reference voltage which is electricallyconnected to the reference electrode. An amplifier is connected toreceive power from the power source and to receive the voltage signalfrom the sensor electrode and the power source reference voltage. Theamplifier produces an output signal which is proportional to the voltagesignal relative to the power source reference voltage. A filter portionreceives the output signal from the amplifier and attenuates electricalactivity unrelated to the signal of interest while passing the signal ofinterest.

A method is described for use by a user in which a measurablecharacteristic of electrical activity (MCEA) in the pre-frontal lobe ofthe user's brain is predefined which measurably corresponds to a levelof certain present time emotional state of the user. The MCEA isisolated from other electrical activity in the user's brain. Mediamaterial is provided which when interacted with by the user in aparticular way can change the present time emotional state of the userin a way which correspondingly changes the MCEA. The user is caused tointeract with the media material in said particular way, and as the userinteracts with the media in said particular way, changes are measured inthe user's MCEA, if any.

A system is disclosed for use by a given user in which there isestablished a predefined measurable characteristic of electricalactivity (MCEA) in the pre-frontal lobe of the given user's brain thatmeasurably corresponds to a level of certain present time emotionalstate of the given user. The system includes a media material which wheninteracted with by the given user in a particular way can change thepresent time emotional state of the user in a way which correspondinglychanges the MCEA. The system also includes means for isolating the MCEAfrom other electrical activity in the given user's brain, and means formeasuring changes in the given user's MCEA, if any, as he or sheinteracts with the media in said particular way.

A method is also disclosed where a system which involves using mediamaterial for guiding a human user to release limiting emotionsexperienced by the user when the user thinks particular thoughts whichcauses the user to experience emotional pain. The release ischaracterized by different levels which are based on how strongly theuser experiences the limiting emotions when confronted with theparticular thoughts. The user has a greater release level when the userhas less limiting emotions related to the particular thoughts and theuser has lower release levels when the user has more limiting emotionsrelated to the particular thoughts. An association is predefined betweena characteristic of electrical activity in a pre-frontal lobe of a humanbrain and levels of release that are being experienced. The user isexposed to a stimulus from the media material relating to the particularthoughts at a particular time which causes the user to experience aparticular one or more of the limiting emotions. Characteristics ofelectrical activity in the user's brain are determined at the particulartime to establish the level of release at the particular time, and therelease level is indicated to the user.

An apparatus is disclosed for use in a system which involves using mediamaterial for guiding a human user to release limiting emotionsexperienced by the user when the user thinks particular thoughts whichcauses the user to experience emotional pain. The release ischaracterized by different levels which are based on how strongly theuser experiences the limiting emotions when confronted with theparticular thoughts. The user has a greater release level when the userhas less limiting emotions related to the particular thoughts and theuser has lower release levels when the user has more limiting emotionsrelated to the particular thoughts. The apparatus includes a memorydevice for storing a predefined association between a characteristic ofelectrical activity in a pre-frontal lobe of a human brain, and levelsof release that are being experienced. A sensor circuit is used forsensing the characteristic of electrical activity in a pre-frontal lobeof the user's brain and for generating a signal of interest based on thesensed characteristic. A processor is connected to receive the signal ofinterest from the sensor and the association from the memory device andto generate a release level signal based on the application of theassociation to the signal of interest. An indicator is used forreceiving the release level signal and indicating the release level tothe user.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a system which uses a sensor device whichmeasures electrical activity to determine a present time emotional stateof a user.

FIG. 2 is an illustration of a program which contains a display of alevel of the present time emotional state of the user and has controlsfor media material used in guiding the user in relation to the presenttime emotional state of the user.

FIG. 3 is a diagram of one example in which the media material guidesthe user based on the present time emotional state of the user.

FIG. 4 is a diagram of another example in which the media materialguides the user based on the present time emotional state of the user.

FIG. 5 is a diagram of yet another example in which the media materialguides the user based on the present time emotional state of the user.

FIG. 6 is a perspective view of the sensor device shown in FIG. 1 .

FIG. 7 is a block diagram of the sensor device and a computer shown inFIG. 1 .

FIG. 8 is a circuit diagram of an amplifier used in the sensor deviceshown in FIG. 7 .

FIG. 9 is a circuit diagram of a filter stage used in the sensor deviceshown in FIG. 7 .

FIG. 10 is a circuit diagram of a resistor-capacitor RC filter used inthe sensor device shown in FIG. 7 .

FIG. 11 is a circuit diagram of the amplifier, three filter stages andthe RC filter shown in FIGS. 8, 9 and 10 .

FIG. 12 is a block diagram of a digital processor of the sensor deviceshown in FIG. 7 .

DETAILED DESCRIPTION

A system 30 which incorporates the present discussion is shown in FIG. 1. Exemplary system 30 includes a sensor device 32 which is connected toa user 34 for sensing and isolating a signal of interest from electricalactivity in the user's pre-frontal lobe. The signal of interest has ameasurable characteristic of electrical activity, or signal of interest,which relates to a present time emotional state (PTES) of user 34. PTESrelates to the emotional state of the user at a given time. Forinstance, if the user is thinking about something that causes the useremotional distress, then the PTES is different than when the user isthinking about something which has a calming affect on the emotions ofthe user. In another example, when the user feels a limiting emotionregarding thoughts, then the PTES is different than when the user feelsa state of release regarding those thoughts. Because of the relationshipbetween the signal of interest and PTES, system 30 is able to determinea level of PTES experienced by user 34 by measuring the electricalactivity and isolating a signal of interest from other electricalactivity in the user's brain.

In the present example, sensor device 32 includes a sensor electrode 36which is positioned at a first point and a reference electrode 38 whichis positioned at a second point. The first and second points are placedin a spaced apart relationship while remaining in close proximity to oneanother. The points are preferably within about 8 inches of one another,and in one instance the points are about 4 inches apart. In the presentexample, sensor electrode 36 is positioned on the skin of the user'sforehead and reference electrode 38 is connected to the user's ear. Thereference electrode can also be attached to the user's forehead, whichmay include positioning the reference electrode over the ear of theuser.

Sensor electrode 36 and reference electrode 38 are connected to anelectronics module 40 of sensor device 32, which is positioned near thereference electrode 38 to that they are located substantially in thesame noise environment. The electronics module 40 may be located at orabove the temple of the user or in other locations where the electronicsmodule 40 is in close proximity to the reference electrode 38. In thepresent example, a head band 42 or other mounting device holds sensorelectrode 36 and electronics module 40 in place near the temple while aclip 44 holds reference electrode 38 to the user's ear. In one instance,the electronics module and reference electrode are positioned relativeto one another such that they are capacitively coupled.

Sensor electrode 36 senses the electrical activity in the user'spre-frontal lobe and electronics module 40 isolates the signal ofinterest from the other electrical activity present and detected by thesensor electrode. Electronics module 40 includes a wireless transmitter46, (FIG. 6 ), which transmits the signal of interest to a wirelessreceiver 48 over a wireless link 50. Wireless receiver 48, FIG. 1 ,receives the signal of interest from electronics module 40 and connectsto a port 52 of a computer 54, or other device having a processor, witha port connector 53 to transfer the signal of interest from wirelessreceiver 48 to computer 54. Electronics module 40 includes an LED 55(FIG. 6 ), and wireless receiver 48 includes an LED 57 which bothilluminate when the wireless transmitter and the wireless receiver arepowered.

In the present example, levels of PTES derived from the signal ofinterest are displayed in a meter 56, (FIGS. 1 and 2 ), on a computerscreen 58 of computer 54. In this instance, computer 54, and screen 58displaying meter 56 serve as an indicator. Levels of detail of meter 56can be adjusted to suit the user. Viewing meter 56 allows user 34 todetermine their level of PTES at any particular time in a manner whichis objective. The objective feedback obtained from meter 56 is used forguiding the user to improve their PTES and to determine levels of PTESrelated to particular memories or thoughts which can be brought up inthe mind of user 34 when the user is exposed to certain stimuli. Meter56 includes an indicator 60 which moves vertically up and down anumbered bar 62 to indicate the level of the user's PTES. Meter 56 alsoincludes a minimum level indicator 64 which indicates a minimum level ofPTES achieved over a certain period of time or during a session in whichuser 34 is exposed to stimuli from media material 66. Meter 56 can alsoinclude the user's maximum, minimum and average levels of release duringa session. Levels of PTES may also be audibly communicated to the user,and in this instance, the computer and speaker serve as the indicator.The levels can also be indicated to the user by printing them on paper.

In another instance, different release levels relating to reaction tothe same media material can be stored over time on a memory device.These different release levels can be displayed next to one another toinform the user on his or her progress in releasing the negativeemotions related to the media material.

In system 30, media material 66 is used to expose user 34 to stimulidesigned to cause user 34 to bring up particular thoughts or emotionswhich are related to a high level of PTES in the user. In the presentexample, media material 66 includes audio material that is played thoughcomputer 54 over a speaker 68. Media material 66 and meter 56 areintegrated into a computer program 70 which runs on computer 54 and isdisplayed on computer screen 58. Media material 66 is controlled usingon-screen buttons 72, in this instance. Computer program 70 also hasother menu buttons 74 for manipulation of program functions and anindicator 76 which indicates connection strength of the wireless link50. Program 70 is typically stored in memory of computer 54, this oranother memory device can also contain a database for storing selfreported journals and self-observed progress.

In some instances, program 70 may require a response or other input fromuser 34. In these and other circumstances, user 34 may interact withprogram 70 using any one or more suitable peripheral or input device,such as a keyboard 78, mouse 80 and/or microphone 82. For instance,mouse 80 may be used to select one of buttons 72 for controlling mediamaterial 66.

Media material 66 allows user 34 to interact with computer 54 for selfor assisted inquiry. Media material 66 can be audio, visual, audio andvisual, and/or can include written material files or other types offiles which are played on or presented by computer 54. Media material 66can be based on one or more processes, such as “The Release Technique”or others. In some instances, generic topics can be provided in the formof audio-video files presented in the form of pre-described exercises.These exercises can involve typical significant life issues or goals formost individuals, such as money, winning, relationships, and many otherpopular topics that allow the user to achieve a freedom state regardingthese topics. The freedom state about the goal can be displayed when avery low level of PTES, (under some preset threshold) is achieved by theuser regarding the goal. The release technique is used as an example insome instances; other processes may also be used with the technologicalapproach described herein.

In one instance, media material 66 involving “The Release Technique”causes user 34 to bring up a limiting emotion or an emotion-ladenexperience type of PTES, which results in a disturbance in the nervoussystem of the user. The process then guides user 34 to normalize thenervous system or release the emotion while the user is focused on theperceived cause of the disturbance. When it is determined that the levelof PTES, or release level in this instance, is below a preset thresholdthen the process is completed.

The signal of interest which relates to the release level PTES are brainwaves or electrical activity in the pre-frontal lobe of the user's brainin the range of 4-12 Hz. These characteristic frequencies of electricalactivity are in the Alpha and Theta bands. Alpha band activity is in the8 to 12 Hz range and Theta band activity is in the 4 to 7 Hz range. Alinear relationship between amplitudes of the Alpha and Theta bands isan indication of the release level. When user 34 is in a non-releasestate, the activity is predominantly in the Theta band and the Alphaband is diminished; and when user 34 is in a release state the activityis predominantly in the Alpha band and the energy in the Theta band isdiminished.

When user 34 releases the emotion, totality of thoughts that remain inthe subconscious mind is lowered in the brain as the disturbance isincrementally released from the mind. A high number of thoughts in thesubconscious mind results in what is known as unhappiness or melancholyfeelings, which are disturbances in the nervous system. A low number ofthoughts in the subconscious mind results in what is known as happinessor joyful feelings, which results in a normalization or absence ofdisturbances in the nervous system.

An exemplary method 84 which makes use of one or more self or assistedinquiry processes is shown in FIG. 3 . Method 84 begins at a start 86from which the method moves to a step 88. At step 88, program 70 usesstimuli in media material 66 to guide user 34 to bring up thoughts orsubjects which causes an emotional disturbance in the PTES such as alimiting emotion. In the present example, media material 66 involvesquestions or statements directed to user 34 through speaker 68. In thisand other instances, the computer can insert statements about goals orissue which were input by the user into the media material 66. Forexample, user 34 may input a goal statement using keyboard 78 and thecomputer may generate a voice which inserts the goal statement into themedia material. In another example, the user may input the goalstatement using microphone 82 and the computer may insert the goalstatement into the media material.

Method 84 then proceeds to step 90 where program 70 uses media material66 to guide user 34 to release the limiting emotions while stillfocusing on the thought or subject which causes the limiting emotion.From step 90, the program proceeds to step 92 where a determination ismade as to whether user 34 has released the limiting emotions. Thisdetermination is made using the signal of interest from sensor device32. In the instance case, the level of release is indicated by theposition of indicator 60 on bar 62 in meter 56, as shown in FIG. 2 . Ifthe meter indicates that user 34 has released the limiting emotions toan appropriate degree, such as below the preset threshold, then thedetermination at 92 is yes and method 84 proceeds to end at step 94. Ifthe determination at 92 is that user 34 has not release the limitingemotions to an appropriate degree, then the determination at 92 is no,and method 84 returns to step 88 to again guide the user to bring up thethought or subject causing the limiting emotion. Method 84 can becontinued as long as needed for user 34 to release the limiting emotionsand achieve the freedom state. Processes can also include clean upsessions in which the user is guided by the media material to releasemany typical limiting emotions to assist the user in achieving a lowthought frequency releasing the limiting emotions.

By observing meter 56 while attempting to release the limiting emotions,user 34 is able to correlate feelings with the release of limitingemotions. Repeating this process reinforces the correlation so that theuser learns what it feels like to release and is able to releaseeffectively with or without the meter 56 by having an increasedreleasing skill. A loop feature allows the user to click on a button toenter a loop session in which the releasing part of an exercise isrepeated continuously. The levels of the user's PTES are indicated tothe user and the levels are automatically recorded during these loopsessions for later review. Loop sessions provide a fast way in which toguide a user to let go of limiting emotions surrounding particularthoughts related to particular subjects. The loop session does notrequire the user to do anything between repetitions which allows them tomaintain the desirable state of low thought activity, or the releasestate. Loop sessions can be included in any process for guiding the userto improve their PTES.

Computer 54 is also able to record release levels over time to a memorydevice to enable user 34 to review the releasing progress achievedduring a recorded session. Other sessions can be reviewed along side ofmore recent sessions to illustrate the progress of the user's releasingability by recalling the sessions from the memory device.

System 30 is also used for helping user 34 to determine what particularthoughts or subjects affect the user's PTES. An example of this use is amethod 100, shown in FIG. 4 . Method 100 begins at start 102 from whichthe method proceeds to step 104. At step 104, user 34 is exposed to asession of media content 42 which contains multiple stimuli that arepresented to user 34 over time. Method 100 proceeds to step 106 wherethe levels of PTES of user 34 are determined during the session whilethe user is exposed to the multiple stimuli. Following step 106 methodproceeds to step 108 where stimulus is selected from the media content42 which resulted in negative affects on the PTES, such as highemotional limitations. Method 100 therefore identifies for the userareas which results in the negative affects on the PTES. Method 100 thenproceeds to step 110 where the selected stimuli is used in a process tohelp the user release the negative emotions. Method 100 ends at step112.

In one example, program 70 uses a method 120, FIG. 5 , which includes aquestioning pattern called “Advantages/Disadvantages.” In this method,the media file asks user 34 several questions in sequence related toadvantages/disadvantages of a “certain subject”, which causes the userto experience negative emotions. Words or phrases of the “certainsubject” can be entered into the computer by the user using one of theinput devices, such as keyboard 78, mouse 80 and/or microphone 82 whichallows the computer to insert the words or phrases into the questions.System 30 may also have goal documents that have the user's goalstatements displayed along with the questioning patterns about the goaland release level data of the user regarding the goal. As an example,the user may have an issue which relates to control, such as a fear ofbeing late for an airline flight. In this instance, the user would entersomething like “fear of being late for a flight” as the “certainsubject.”

Series of questions related to advantages and disadvantage can bealternated until the state of release, or other PTES, is stabilized aslow as possible, that is with the greatest amount of release. Method120, shown in FIG. 5 , starts at a start 122 from which it proceeds tostep 124 where program 70 asks user 34 “What advantage/disadvantage isit to me to feel limited by the certain subject?” Program 70 then waitsfor feedback from the user through one of the input devices.

Program then proceeds to step 126 where program 70 asks user 34 “Doesthat bring up a wanting approval, wanting control or wanting to be safefeeling?” Program 70 waits for a response from user 34 from the inputdevice and deciphers which one of the feelings the user responds with,such as “control feeling” for instance. Method 120 then proceeds to step128 where program 70 questions the user based on the response given tostep 128 by asking “Can you let that wanting control feeling go?” inthis instance. At this point method 120 proceeds to step 130 wheresensor device 32 determines the signal of interest to determine therelease level of user 34. The release level is monitored and the mediafile stops playing when the release level has stabilized at its lowestpoint. At this time method 120 proceeds to step 132 and the session iscomplete. When the session is complete, user 34 will feel a sense offreedom regarding the certain subject. If some unwanted emotionalresidue is left, this same process can be repeated until completefreedom regarding the issue is realized by the user.

The above method is an example of “polarity releasing” in which anindividual is guided to think about positives and negatives about acertain subject or particular issue, until the mind gives up on thenegative emotions generated by the thoughts. There are other polarityreleasing methods, such as “Likes/Dislikes” and other concepts andmethods that help user's to achieve lower though frequency which mayalso be used along with a sensor device such as sensor device 32 for thepurposes described herein.

Program 70 can store the history of responses to media on a memorydevice, and combine multiple iterations of responses to the same mediain order to create a chart of improvement for user 34. Plotting theseresponses on the same chart using varying colors and dimensional effectsdemonstrates to user 34 the various PTES reactions over time to the samemedia stimulus, demonstrating improvement.

Program 70 can store reaction to live content as well. Live content canconsist of listening to a person or audio in the same physical location,or listening to audio streaming over a telecommunications medium liketelephone or the Internet, or text communications. Program 70 can sendthe PTES data from point-to-point using a communication medium like theInternet. With live content flowing in one direction, and PTES dataflowing in the other, the deliverer of live content has a powerful newability to react and change the content immediately, depending on thePTES data reaction of the individual. This deliverer may be a person ora web server application with the ability to understand and react tochanging PTES.

Program 70 can detect the version of the electronic module 40 latently,based on the type of data and number of bytes being sent. Thisinformation is used to turn on and off various features in the program70, depending on the feature's availability in the electronic module 40.

With certain types of computers and when certain types of wireless linksare used, an incompatibility between wireless receiver 48 and computer54 may occur. This incompatibility between an open host controllerinterface (OHCI) of the computer 54 and a universal host controllerinterface (UHCI) chip in the wireless receiver 48 causes a failure ofcommunication. Program 70 has an ability to detect the symptom of thisspecific incompatibility and report it to the user. The detection schemelooks for a single response to a ping ‘P’ from the wireless receiver 48,and all future responses to a ping are ignored. Program 70 then displaysa modal warning to the user suggesting workarounds for theincompatibility.

Program 70 detects the disconnecting of wireless link 50 by continuallychecking for the arrival of new data. If new data stops coming in, itassumes a wireless link failure, and automatically pauses the mediabeing played and recording of PTES data. On detection of new data cominginto the computer 54, the program 70 automatically resumes the media andrecording.

Program 70 can create exercises and set goals for specific PTES levels.For example, it asks the user to set a target level of PTES andcontinues indefinitely until the user has reached that goal. Program 70can also store reactions during numerous other activities. These otheractivities include but are not limited to telephone conversations,meetings, chores, meditation, and organizing. In addition, program 70can allow users to customize their sessions by selecting audio, title,and length of session.

Other computing devices, which can include processor based computingdevices, (not shown) can be used with sensor device 32 to play mediamaterial 66 and display or otherwise indicate the PTES. These devicesmay be connected to the sensor device 32 utilizing an integratedwireless receiver rather than the separate wireless receiver 48 whichplugs into the port of the computer. These devices are more portablethan computer 54 which allows the user to monitor the level PTESthroughout the day or night which allows the user to liberate thesubconscious mind more rapidly. These computing devices can include acamera with an audio recorder for storing and transmitting data to thereceiver to store incidents of reactivity on a memory device for reviewat a later time. These computing devices can also upload reactivityincidents, intensity of these incidents and/or audio-video recordings ofthese incidents into computer 54 where the Attachment and Aversionsprocess or other process can be used to permanently reduce or eliminatereactivity regarding these incidents.

One example of sensor device 32 is shown in FIGS. 6 and 7 . Sensordevice 32 includes sensor electrode 36, reference electrode 38 andelectronics module 40. The electronics module 40 amplifies the signal ofinterest by 1,000 to 100,000 times while at the same time insuring that60 Hz noise is not amplified at any point. Electronics module 40isolates the signal of interest from undesired electrical activity.

Sensor device 32 in the present example also includes wireless receiver48 which receives the signal of interest from the electronics moduleover wireless link 50 and communicates the signal of interest tocomputer 54. In the present example, wireless link 50 usesradiofrequency energy; however other wireless technologies may also beused, such as infrared. Using a wireless connection eliminates the needfor wires to be connected between the sensor device 32 and computer 54which electrically isolates sensor device 32 from computer 54.

Reference electrode 38 is connected to a clip 148 which is used forattaching reference electrode 38 to an ear 150 of user 34, in thepresent example. Sensor electrode 36 includes a snap or other springloaded device for attaching sensor electrode 36 to headband 42. Headband42 also includes a pocket for housing electronics module 40 at aposition at the user's temple. Headband 42 is one example of an elasticband which is used for holding the sensor electrode and/or theelectronics module 40, another types of elastic bands which provide thesame function could also be used, including having the elastic band forma portion of a hat.

Other types of mounting devices, in addition to the elastic bands, canalso be used for holding the sensor electrode against the skin of theuser. A holding force holding the sensor electrode against the skin ofthe user can be in the range of 1 to 4 oz. The holding force can be, forinstance, 1.5 oz.

In another example of a mounting device involves a frame that is similarto an eyeglass frame, which holds the sensor electrode against the skinof the user. The frame can also be used for supporting electronicsmodule 40. The frame is worn by user 34 in a way which is supported bythe ears and bridge of the nose of the user, where the sensor electrode36 contacts the skin of the user.

Sensor electrode 36 and reference electrode 38 include conductivesurface 152 and 154, respectively, that are used for placing in contactwith the skin of the user at points where the measurements are to bemade. In the present example, the conductive surfaces are composed of anon-reactive material, such as copper, gold, conductive rubber orconductive plastic. Conductive surface 152 of sensor electrode 36 mayhave a surface area of approximately ½ square inch. The conductivesurfaces 152 are used to directly contact the skin of the user withouthaving to specially prepare the skin and without having to use asubstance to reduce a contact resistance found between the skin and theconductive surfaces.

Sensor device 32 works with contact resistances as high as 500,000 ohmswhich allows the device to work with conductive surfaces in directcontact with skin that is not specially prepared. In contrast, specialskin preparation and conductive gels or other substances are used withprior EEG electrodes to reduce the contact resistances to around 20,000ohms or less. One consequence of dealing with higher contact resistanceis that noise may be coupled into the measurement. The noise comes fromlights and other equipment connected to 60 Hz power, and also fromfriction of any object moving through the air which creates staticelectricity. The amplitude of the noise is proportional to the distancebetween the electronics module 40 and the reference electrode 38. In thepresent example, by placing the electronics module over the temple area,right above the ear and connecting the reference electrode to the ear,the sensor device 32 does not pick up the noise, or is substantiallyunaffected by the noise. By positioning the electronics module in thesame physical space with the reference electrode and capacitivelycoupling the electronics module with the reference electrode ensuresthat a local reference potential 144 in the electronics module and theear are practically identical in potential. Reference electrode 38 iselectrically connected to local reference potential 144 used in a powersource 158 for the sensor device 32.

Power source 158 provides power 146 to electronic components in themodule over power conductors. Power source 158 provides the sensordevice 32 with reference potential 144 at 0 volts as well as positiveand negative source voltages, −VCC and +VCC. Power source 158 makes useof a charge pump for generating the source voltages at a level which issuitable for the electronics module.

Power source is connected to the other components in the module 40though a switch 156. Power source 158 can include a timer circuit whichcauses electronics module 40 to be powered for a certain time beforepower is disconnected. This feature conserves power for instances whereuser 34 accidentally leaves the power to electronics module 40 turnedon. The power 146 is referenced locally to measurements and does nothave any reference connection to an external ground system since sensorcircuit 32 uses wireless link 50.

Sensor electrode 36 is placed in contact with the skin of the user at apoint where the electrical activity in the brain is to be sensed ormeasured. Reference electrode 38 is placed in contact with the skin at apoint a small distance away from the point where the sensor electrode isplaced. In the present example, this distance is 4 inches, although thedistance may be as much as about 8 inches. Longer lengths may add noiseto the system since the amplitude of the noise is proportional to thedistance between the electronics module and the reference electrode.Electronics module 40 is placed in close proximity to the referenceelectrode 38. This causes the electronics module 40 to be in the same ofelectrical and magnetic environment is the reference electrode 38 andelectronics module 40 is connected capacitively and through mutualinductance to reference electrode 38. Reference electrode 38 andamplifier 168 are coupled together into the noise environment, andsensor electrode 36 measures the signal of interest a short distanceaway from the reference electrode to reduce or eliminate the influenceof noise on sensor device 32. Reference electrode 38 is connected to the0V in the power source 158 with a conductor 166.

Sensor electrode 36 senses electrical activity in the user's brain andgenerates a voltage signal 160 related thereto which is the potential ofthe electrical activity at the point where the sensor electrode 36contacts the user's skin relative to the local reference potential 144.Voltage signal 160 is communicated from the electrode 36 to electronicsmodule 40 over conductor 162. Conductors 162 and 166 are connected toelectrodes 36 and 38 in such a way that there is no solder on conductivesurfaces 152 and 154. Conductor 162 is as short as practical, and in thepresent example is approximately 3 inches long. When sensor device 32 isused, conductor 162 is held a distance away from user 34 so thatconductor 162 does not couple signals to or from user 34. In the presentexample, conductor 162 is held at a distance of approximately ½″ fromuser 34. No other wires, optical fibers or other types of extensionsextend from the electronics module 40, other than the conductors 162 and166 extending between module 40 and electrodes 36 and 38, since thesetypes of structure tend to pick up electronic noise.

The electronics module 40 measures or determines electrical activity,which includes the signal of interest and other electrical activityunrelated to the signal of interest which is undesired. Electronicsmodule 40 uses a single ended amplifier 168, (FIGS. 7 and 8 ), which isclosely coupled to noise in the environment of the measurement with thereference electrode 38. The single ended amplifier 168 provides a gainof 2 for frequencies up to 12 Hz, which includes electrical activity inthe Alpha and Theta bands, and a gain of less than 1 for frequencies 60Hz and above, including harmonics of 60 Hz.

Amplifier 168, FIGS. 8 and 11 , receives the voltage signal 160 fromelectrode 36 and power 146 from power source 158. Single ended amplifier168 generates an output signal 174 which is proportional to voltagesignal 160. Output signal 174 contains the signal of interest. In thepresent example, voltage signal 160 is supplied on conductor 162 to aresistor 170 which is connected to non-inverting input of highimpedance, low power op amp 172. Output signal 174 is used as feedbackto the inverting input of op amp 172 through resistor 176 and capacitor178 which are connected in parallel. The inverting input of op amp 172is also connected to reference voltage 144 through a resistor 180.

Amplifier 168 is connected to a three-stage sensor filter 182 with anoutput conductor 184 which carries output signal 174. The electricalactivity or voltage signal 160 is amplified by each of the stages 168and 182 while undesired signals, such as those 60 Hz and above, areattenuated by each of the stages. Three-stage sensor filter has threestages 206 a, 206 b and 206 c each having the same design to provide abandpass filter function which allows signals between 1.2 and 12 Hz topass with a gain of 5 while attenuating signal lower and higher thanthese frequencies. The bandpass filter function allows signals in theAlpha and Theta bands to pass while attenuating noise such as 60 Hz andharmonics of the 60 Hz. The three stage sensor filter 182 removesoffsets in the signal that are due to biases and offsets in the parts.Each of the three stages is connected to source voltage 146 andreference voltage 144. Each of the three stages generates an outputsignal 186 a, 186 b and 186 c on an output conductor 188 a, 186 b and188 c, respectively.

In the first stage 206 a, FIGS. 9 and 11 , of three-stage sensor filter182, output signal 174 is supplied to a non-inverting input of a firststage op-amp 190 a through a resistor 192 a and capacitor 194 a. Acapacitor 196 a and another resistor 198 a are connected between thenon-inverting input and reference voltage 144. Feedback of the outputsignal 186 a from the first stage is connected to the inverting input ofop amp 190 a through a resistor 200 a and a capacitor 202 a which areconnected in parallel. The inverting input of op amp 190 a is alsoconnected to reference voltage 144 through resistor 204 a.

Second and third stages 206 b and 206 c, respectively, are arranged inseries with first stage 206 a. First stage output signal 186 a issupplied to second stage 206 b through resistor 192 b and capacitor 194b to the non-inverting input of op-amp 190 b. Second stage output signal186 b is supplied to third stage 206 c through resistor 192 c andcapacitor 194 c. Resistor 198 b and capacitor 196 b are connectedbetween the non-inverting input of op-amp 190 b and reference potential144, and resistor 198 c and capacitor 196 c are connected between thenon-inverting input of op-amp 190 c and reference potential 144.Feedback from output conductor 188 b to the inverting input of op-amp190 b is through resistor 200 b and capacitor 202 b and the invertinginput of op-amp 190 b is also connected to reference potential 144 withresistor 204 b. Feedback from output conductor 188 c to the invertinginput of op-amp 190 c is through resistor 200 c and capacitor 202 c andthe inverting input of op-amp 190 c is also connected to referencepotential 144 with resistor 204 c.

Three stage sensor filter 182 is connected to an RC filter 208, FIGS. 10and 11 , with the output conductor 188 c which carries the output signal186 c from third stage 206 c of three stage sensor filter 182, FIG. 7 .RC filter 208 includes a resistor 210 which is connected in series to anoutput conductor 216, and a capacitor 212 which connects betweenreference potential 144 and output conductor 216. RC filter serves as alow pass filter to further filter out frequencies above 12 Hz. RC filter208 produces a filter signal 214 on output conductor 216. RC filter 208is connected to an analog to digital (A/D) converter 218, FIG. 7 .

A/D converter 218 converts the analog filter signal 214 from the RCfilter to a digital signal 220 by sampling the analog filter signal 214at a sample rate that is a multiple of 60 Hz. In the present example thesample rate is 9600 samples per second. Digital signal 220 is carried toa digital processor 224 on an output conductor 222.

Digital processor 224, FIGS. 7 and 12 provides additional gain, removalof 60 Hz noise, and attenuation of high frequency data. Digitalprocessor 224 many be implemented in software operating on a computingdevice. Digital processor 224 includes a notch filter 230, FIG. 12 whichsums 160 data points of digital signal 220 at a time to produce a 60 Hzdata stream that is free from any information at 60 Hz. Following notchfilter 230 is an error checker 232. Error checker 232, removes datapoints that are out of range from the 60 Hz data stream. These out ofrange data points are either erroneous data or they are cause by someexternal source other than brain activity.

After error checker 232, digital processor 224 transforms the datastream using a discreet Fourier transformer 234. While prior EEG systemsuse band pass filters to select out the Alpha and Theta frequencies,among others, these filters are limited to processing and selecting outcontinuous periodic functions. By using a Fourier transform, digitalprocessor 224 is able to identify randomly spaced events. Each event hasenergy in all frequencies, but shorter events will have more energy inhigher frequencies and longer events will have more energy in lowerfrequencies. By looking at the difference between the energy in Alphaand Theta frequencies, the system is able to identify the predominanceof longer or shorter events. The difference is then scaled by the totalenergy in the bands. This causes the output to be based on the type ofenergy and removes anything tied to amount of energy.

The Fourier transformer 234 creates a spectrum signal that separates theenergy into bins 236 a to 236 o which each have a different width offrequency. In one example, the spectrum signal has 30 samples andseparates the energy spectrum into 2 Hz wide bins; in another example,the spectrum signal has 60 samples and separates the bins into 1 Hz widebins. Bins 236 are added to create energy signals in certain bands. Inthe present example, bins 236 between 4 and 8 Hz are passed to a summer238 which sums these bins to create a Theta band energy signal 240; andbins between 8 and 12 Hz are passed to a summer 242 which sums thesebins to create an Alpha band energy signal 244.

In the present example, the Alpha and Theta band energy signals 240 and244 passed to a calculator 246 which calculates(Theta−Alpha)/Theta+Alpha) and produces an output signal 226 on aconductor 228 as a result.

Output signal 226, FIG. 7 , is passed to wireless transmitter 46 whichtransmits the output signal 226 to wireless receiver 48 over wirelesslink 50. In the present example, output signal 226 is the signal ofinterest which is passed to computer 54 through port 52 and which isused by the computer to produce the PTES for display in meter 56.

Computer 54 may provide additional processing of output signal 226 insome instances. In the example using the Release Technique, the computer54 manipulates output signal 226 to determine relative amounts of Alphaand Theta band signals in the output signal to determine levels ofrelease experienced by user 34.

A sensor device utilizing the above described principles and feature canbe used for determining electrical activity in other tissue of the userin addition to the brain tissue just described, such as electricalactivity in muscle and heart tissue. In these instances, the sensorelectrode is positioned on the skin at the point where the electricalactivity is to be measured and the reference electrode and electronicsmodule are positioned nearby with the reference electrode attached to apoint near the sensor electrode. The electronics module, in theseinstances, includes amplification and filtering to isolate thefrequencies of the muscle or heart electrical activity while filteringout other frequencies.

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations thereof. It is thereforeintended that the following appended claims and claims hereafterintroduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

What is claimed is:
 1. A headset to gather electroencephalographicsignals from a person, the headset comprising: a headband to be wornaround a head of the person; a sensor electrode; a reference electrode;and an electronics module including a housing and electronics circuitryin the housing, the sensor electrode and the electronics module carriedby the headband such that when the headband is worn on the head of theperson, the sensor electrode is disposed on a forehead of the personover a pre-frontal lobe of the person and the housing with theelectronics circuitry is disposed over a temple of the person, thesensor electrode, when disposed on the forehead of the person,configured to obtain a signal of interest, an undesired signal, andnoise, the sensor electrode electrically coupled with the electronicscircuitry via a first connector, the reference electrode electricallycoupled with the electronics circuitry via a second connector, theelectronics circuitry including: a front end amplifier circuit, thefirst connector electrically coupled with a first input of the front endamplifier circuit and the second connector electrically coupled with asecond input of the front end amplifier circuit, the front end amplifiercircuit configured to (1) amplify the signal of interest and theundesired signal occurring in a first frequency range and (2) attenuatethe noise occurring in a second frequency range, an output of the frontend amplifier circuit electrically coupled to the second input via aparallel resistor and capacitor; a filter electrically coupled with theoutput of the front end amplifier circuit, the filter configured toreceive an output signal from the front end amplifier circuit containingthe signal of interest and the undesired signal, the filter configuredto isolate the signal of interest by attenuating the undesired signal;and a processor configured to operate on the signal of interest from thefilter.
 2. The headset of claim 1, wherein the electronics module is ina pocket of the headband.
 3. The headset of claim 1, further including aclip to be attached to an ear of the person, the reference electrodecoupled to the clip.
 4. The headset of claim 1, wherein the electronicscircuitry includes a power source having a power source referenceterminal electrically coupled with the reference electrode.
 5. Theheadset of claim 1, wherein the output signal of the front end amplifiercircuit is an analog output signal, the headset further including aconverter to convert the analog output signal to a digital outputsignal.
 6. The headset of claim 5, wherein the processor is configuredto transform the digital output signal using a Fourier transform todetermine an energy spectrum of the digital output signal, the energyspectrum including a plurality of bins representing energy incorresponding frequencies of the digital output signal.
 7. The headsetof claim 6, wherein the processor is configured to sum the energy in thebins corresponding to frequencies of from 4 hertz (Hz) to 8 Hz to createa Theta band energy signal.
 8. The headset of claim 7, wherein theprocessor is configured to sum the energy in the bins corresponding tofrequencies of from 8 Hz to 12 Hz to create an Alpha band energy signal.9. The headset of claim 8, wherein the processor is configured todetermine a ratio of the Alpha band energy signal and the Theta bandenergy signal.
 10. The headset of claim 8, wherein the electronicscircuitry includes a wireless transmitter to transmit an output of acalculation based on the Alpha band energy signal and the Theta bandenergy signal to a wireless receiver of an electronic device.
 11. Aheadset to gather electroencephalographic signals from a person, theheadset comprising: a sensor electrode; a reference electrode; anelectronics module including a housing and electronics circuitry in thehousing; and means for supporting the sensor electrode on a forehead ofthe person over a pre-frontal lobe of the person and the housing withthe electronics circuitry over a temple of the person, the sensorelectrode, when disposed on the forehead of the person, to obtain asignal of interest, an undesired signal, and noise, the sensor electrodeelectrically coupled with the electronics circuitry via a firstconnector, the reference electrode electrically coupled with theelectronics circuitry via a second connector, the electronics circuitryincluding: a front end amplifier, the first connector electricallycoupled with a first input of the front end amplifier and the secondconnector electrically coupled with a second input of the front endamplifier, the front end amplifier configured to (1) amplify the signalof interest and the undesired signal occurring in a first frequencyrange and (2) attenuate the noise occurring in a second frequency range,an output of the front end amplifier electrically coupled to the secondinput via a parallel resistor and capacitor; a filter electronicallycoupled with the output of the front end amplifier, the filterconfigured to receive an output signal from the front end amplifiercontaining the signal of interest and the undesired signal, the filterconfigured to isolate the signal of interest by attenuating theundesired signal; and means for analyzing the signal of interest fromthe filter.
 12. The headset of claim 11, further including means forsupporting the reference electrode on an ear of the person.
 13. Theheadset of claim 11, wherein the electronics circuitry includes a powersource having a power source reference terminal electronically coupledwith the reference electrode.
 14. The headset of claim 11, wherein theoutput of the front end amplifier is an analog output signal, theheadset further including means for converting the analog output signalto a digital output signal.
 15. The headset of claim 14, furtherincluding means for determining an energy spectrum of the digital outputsignal, the energy spectrum including a plurality of bins representingenergy in corresponding frequencies of the digital output signal. 16.The headset of claim 15, wherein the means for determining is configuredto sum the energy in the bins corresponding to frequencies of from 4hertz (Hz) to 8 Hz to create a Theta band energy signal.
 17. The headsetof claim 16, wherein the means for determining is configured to sum theenergy in the bins corresponding to frequencies of from 8 Hz to 12 Hz tocreate an Alpha band energy signal.
 18. The headset of claim 17, furtherincluding means for generating an output signal of a ratio of the Alphaband energy signal and the Theta band energy signal.
 19. The headset ofclaim 18, wherein the electronics circuitry includes means fortransmitting the output signal to a wireless receiver of an electronicdevice.